Asymmetrical Digital Subscriber Line (ADSL) modems offer a high speed alternative (up to 8 Mbps, depending on line conditions) to conventional analog modem technology. U.S. patent application Ser. No. 09/135,221, (now U.S. Pat. No. 6,498,806) filed, Aug. 17, 1998, issued Dec. 24, 2002 and assigned to the same assignee as this application, is incorporated by reference herein. Patent application Ser. No. 09/135,221, hereafter referred to as the 98 application, is directed to a shared asymmetric subscriber line modem. The 98 application introduced the concept of using a single multidrop modem in a central office Digital Subscriber Line Access Multiplexer (DSLAM) to drive multiple subscriber lines. Line sharing was implemented by allocating a small portion of the available bandwidth to a control channel which was used to indicate to a group of client modems which one of the client modems was the intended recipient of a corresponding physical frame of data. This solution resulted in a significant simplification of the digital portion of the ADSL server modem as well as the Digital to Analog converter. This solution requires a separate line driver for each of the subscriber lines. While this is not a major cost consideration, the power dissipated in each of these line drivers becomes a limiting factor in achieving higher levels of integration on ADSL server line circuit cards.